1. Technical Field
The present invention relates to an image printing device which performs a duplex printing.
2. Related Art
In the related art, an image printing device configured to perform image printing on both surfaces of a printing paper is known. In the image printing device, the printing paper transported to a printing unit and subjected to the image printing on a first surface thereof through a transporting path defining a U-turn path is subjected to a switchback transport via a transporting path connecting a downstream side and an upstream side of the printing unit, and the printing paper entered again the transporting path is positioned with a second surface thereof opposing the printing unit, so that the printing unit performs the image printing on the second surface.
A plurality of roller pairs configured to hold and transport the printing paper are arranged in the transporting path. The transporting roller pairs include some transporting roller pairs being rotated in the same direction by a drive transmission from a common motor. Therefore, if the transporting roller pairs for the switchback transport of the printing paper backward are rotated in the reverse direction, other transporting roller pairs are rotated in the reverse direction. If the plurality of transporting roller pairs that hold and transport a single printing paper simultaneously are rotated in the opposed direction when the switchback transport of the printing paper is performed, the printing paper is pulled by the plurality of transporting roller pairs. In order to solve the problem as described above, a means to release the drive transmission to one of transporting roller pairs when the other transporting roller pair is rotated is known.
However, providing a mechanism for releasing the drive transmission considering the directions of rotation of the transporting roller pairs in duplex printing may increase complication of the mechanism and increase cost.